Mercutio carries a skeletonized “Dagger 9mm” pistol, actually a Taurus:
The Montague and Capulet boys have ornately engraved and painted magazine floor plates on their pistols:
Note that there are four different kinds of plates:
Mercutio: White vinyl letters on a flat black plate. Appears to be a condensed Helvetica-style font. No border. Full width text. No frame.
Tybalt: White vinyl letters on an embossed black plate. Ultra-condensed bold font, possibly Helvetica. Text split into two groups of three letters. Fancy frame. Romeo and Benvolio also have plates like this.
Old Man Montague: White vinyl letters on an embossed black plate. Ultra-condensed font, possibly Helvetica, slightly less bold than Tybalt’s. Full width text. Fancy frame.
Civilian Background Cars: White painted letters on an embossed black plate. Rounded, narrow font. Text split into two groups of three letters. No frame, but a white vinyl pinstripe border.